Can someone explain/link me to somewhere that explains how to remove all of the mold releasing agent from a piece of plastic please?

 

If you're looking to prep for paint, a good wash in soap and water and a wipe with alcohol or other sovent should do the trick. If it's smooth, you'll also want to scuff it up a bit with sandpaper.

 

Are you painting it? If not just let whoever is do the prep work, because there won't be any price difference. If you're painting it wipe it down with a prepaint cleaner and then wipe it dry. When it dries spray a two thin coats of adhesion promoter. You don't have to scuff it, but it won't hurt. If you do scuff it with a red scotch pad or 400 grit sandpaper. Then wipe it down with the cleaner and spray two coats of adhesion promoter. Wait around 5 minutes after you spray the adhesion promoter and you can start spraying your base.